Goodman GMVC960803BN Error Code EEF: Condensate Switch Open

What Does Code EEF Mean?

The Goodman GMVC960803BN is a 96% AFUE condensing furnace. Pulling that much heat out of the combustion gases cools them below their dew point, so the furnace continuously produces liquid condensate that must drain away through a trap and drain line. To guard against water damage, an auxiliary condensate (float) switch watches the water level, and when water backs up the switch opens, the Integrated Control Module stops the furnace, and the 7-segment display shows EEF.

The most common reason water backs up is a clogged or slime-fouled condensate drain line or trap. Over a season, algae, mildew, and sediment build up inside the tubing and the U-shaped trap and choke off the flow. A drain pan under the evaporator coil that cannot empty, or in winter a drain line frozen where it exits the building, will produce the same rising water level and the same EEF trip.

EEF sits alongside the venting-and-drain family of faults on this board. Because a plugged condensate path also disrupts proper draft, a badly blocked drain can show up first as a pressure-switch complaint such as EE2 (Low Stage Pressure Switch Open), which also lists a blocked drain system among its causes. Clearing a condensate drain is sometimes a homeowner task, but on this model EEF is flagged as pro-only, so the drain line, trap, and coil pan should be cleared and inspected by a technician rather than with an improvised procedure.

What You'll Notice

• The furnace is shut down with EEF on the 7-segment LED display and no heat
• Water is pooling around the base of the furnace or under the indoor coil
• The condensate drain line or its trap looks slimy, discolored, or plugged
• A connected condensate pump reservoir is full or the pump is not running
• In cold weather, the section of drain line running to the outdoors is frozen

Common Causes

How This Is Diagnosed

A technician confirms the float switch actually tripped on water rather than on a wiring fault, then traces the condensate path from the coil drain pan through the trap to the termination, checking for slime, sediment, or a frozen or improperly sloped line. They clear and flush the line and trap, verify the pan drains, and confirm water flows freely and the switch resets before returning the furnace to service; they also check that a blocked drain has not been disturbing draft and the pressure switches.

When to Call a Professional

This code involves components that are not homeowner-serviceable, so have a licensed HVAC technician diagnose and repair it. Keep in mind:

• Water is pooling around the furnace or leaking from the coil cabinet
• EEF returns after the drain appears to have been cleared
• A condensate pump is installed and is not running or is overflowing
• The drain line is frozen where it runs to the exterior
• You suspect the float switch itself is stuck or faulty

✓ Verified against manufacturer service manual — March 2026